To some extent, you can compare two variants using <b>Equal?</b> comparison nodes. There are some issues as 0.0(DBL) will be different from 0(U32) and NaN(DBL) will be equal to NaN(DBL) (IEEE spec requires that (NaN == NaN) should return False).
Take a look at LabVIEW Data Tools in the OpenG Toolkit at http://openg.org . There are tons of VIs to manipulate variant data.
